From 125bac016d60e78120e92904a5b2fc3a5ebf0475 Mon Sep 17 00:00:00 2001
From: Miao Xie <miaox@cn.fujitsu.com>
Date: Thu, 25 Jul 2013 19:22:37 +0800
Subject: [PATCH] Btrfs: cache the extent map struct when reading several pages

When we read several pages at once, we needn't get the extent map object
every time we deal with a page, and we can cache the extent map object.
So, we can reduce the search time of the extent map, and besides that, we
also can reduce the lock contention of the extent map tree.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Reading git-format-patch failed